Mobile devices having antennas that support multi-band communications are known. Many such mobile devices utilize helix or retractable structures, which are typically installed outside of a mobile device, although embedded antennas installed inside of a case or housing of a device are also known. Generally, embedded antennas are preferred over external antennas for mobile communication devices for mechanical and ergonomic reasons. Embedded antennas are protected by the mobile device case or housing and therefore tend to be more durable than external antennas. Whereas external antennas may physically interfere with the surroundings of a mobile device and make a mobile device difficult to use, particularly in limited-space environments, embedded antennas present fewer such challenges.
In some types of mobile devices, however, known embedded structures and design techniques provide relatively poor communication signal radiation and reception, at least in certain operating positions of the mobile devices. One of the biggest challenges for mobile device antenna design is to ensure that the antenna operates effectively in different positions, since antenna position changes as a mobile device is moved.
In addition, where operation of a mobile device in multiple operating frequency bands is desired or required, physical space limitations often preclude the use of separate antennas for each operating frequency band.